FT-ICR Cell Electrodes for Magnetic Field Inhomogeneity Compensation
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Solution Overview
Problem
Magnetic field inhomogeneities in FT-ICR mass spectrometers limit the duration of ion cyclotron motion and resolving power, particularly in instruments with lower magnetic field homogeneity, leading to signal attenuation and decreased mass resolution.
Innovation Solution
The introduction of additional electrodes shaped to create a compensating electric field, which adjusts the cyclotron frequency to be independent of ion oscillation amplitude, effectively counteracting magnetic field inhomogeneities by creating a hyperbolic electric field distribution within the FT-ICR cell.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional electrodes are introduced to compensate magnetic field inhomogeneity, then mass resolution and synchronous ion motion duration are improved, but device complexity increases
Solution Approach 1:
The cell housing is segmented into multiple electrode structures (first and second electrode structures) with specific geometric configurations. Each electrode structure is divided into segments that can be independently controlled, allowing precise compensation of magnetic field inhomogeneity across different spatial regions of the trap cell.
Solution Approach 2:
The electrode structures are designed with position-dependent properties - the first electrode structure has a different geometric configuration than the second electrode structure. This local variation in electrode geometry creates spatially varying electric field distributions that specifically address local magnetic field inhomogeneities in different regions of the trap cell.
2Reliability
If electrode geometries are optimized to create hyperbolic field distribution, then cyclotron frequency stability is improved, but manufacturing precision requirements increase
Solution Approach 1:
The electrode structures are designed with curved surfaces that approximate hyperbolic geometric configurations. The first and second electrode structures feature specific curvature profiles that generate the desired hyperbolic electric field distribution when appropriate voltages are applied, thereby stabilizing the cyclotron frequency of trapped ions.
Solution Approach 2:
The system allows dynamic adjustment of electrode potentials (electrical parameters) to optimize the electric field distribution. By changing the voltage parameters applied to the electrode structures, the system can compensate for manufacturing tolerances and achieve the desired hyperbolic field configuration for stable cyclotron motion.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly extends the time of synchronous ion motion and enhances mass resolution, aligning cyclotron frequencies across various amplitudes, thereby improving the overall performance of FT-ICR mass spectrometers, even with magnets of lower homogeneity.
Implementation Method 1
The introduction of additional electrodes shaped to create a compensating electric field, which adjusts the cyclotron frequency to be independent of ion oscillation amplitude
Implementation Method 2
cyclotron motion of the ions is excited by a radio frequency (RF) field and the frequency of this motion is determined by measuring the current induced
Implementation Method 3
creating a hyperbolic electric field distribution within the FT-ICR cell
Data Source
Figure 1A~1D
Figure 2A~2F
Figure 3
AI summary
A method and apparatus of compensating a magnetic field inhomogeneity in a dynamically harmonized FT-ICR cell is presented, based on adding of extra electrodes into the cell, the extra electrodes being shaped in such a way that the averaged electric field created by these electrodes produces a counter force to the forces caused by the inhomogeneous magnetic field on the cycling ions.